There has been renewed interest in developing vaccine and immunotherapy for the treatment of cancer. The oncofetal antigen, 5T4, is a surface glycoprotein that is expressed on a variety of human adenocarcinomas but rarely on normal tissue. 5T4 plays an important role in tumor progression and metastasis. The expression patterns and functional role in the metastatic process suggest that 5T4 is a good target for vaccine development. A modified vaccinia virus Ankara (MVA) encoding human 5T4 (designated TroVax) demonstrated therapeutic effects in murine tumor models and human T cells recognized 5T4 epitopes in an HLA-restricted manner. The TroVax vaccine has subsequently been evaluated in clinical trials targeting patients with colorectal cancer, renal cell carcinoma and hormone refractory prostate cancer. Herein, we review the results of these clinical studies, discuss the lessons learned through these trials and provide some insight into the future development of TroVax as a cancer vaccine.